A 57‐GHz CMOS VCO with 185.3% tuning‐range enhancement using tunable LC source‐degeneration

Abstract

AbstractA 57‐GHz CMOS voltage‐controlled oscillator (VCO) using tunable LC source‐degeneration for operation frequency and tuning‐range enhancement is demonstrated. The tunable LC source‐degeneration is made by adding two tunable LC tanks, where varactors are used as the needed capacitors, to the source terminals of the cross‐coupled transistor pair of the VCO. Compared with the traditional cross‐coupled transistor pair, the proposed one significantly decreases the equivalent parallel capacitance (CEQ). This in turn results in the increase of both the operation frequency and the tuning range of the VCO. The measurement result shows the tunable LC source‐degeneration achieved a 185.3% enhancement [from 1.36 GHz (53.36–54.72 GHz) to 3.88 GHz (53.36–57.24 GHz)] in tuning range by tuning the varactors of the proposed cross‐coupled transistor pair. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2682–2685, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24706